It looks like most things (or everything?) that we consume, whether it is a food, drink, or something we smoke (like e.g. some drug like marijuana) ends up in some amounts in our hair.
If this is the case, is it theoretically possible that there exists some compound that, when ingested, could affect the color of our hair?
Or alternatively, would it be possible for an ingested chemical to weaken or strengthen the disulfide bonds present in hair structure?